A boron nitride powder (also referred to as a BN powder) has excellent lubricity as compared with other materials, and is gaining attention as a pigment for cosmetics (also referred to as cosmetic products). In particular, for its excellent lubricity, the BN powder is increasingly used as a cosmetic extender recently.
A cosmetic extender is a base for dispersing a color pigment, and significantly influences feelings of use such as “spreadability” (the property of being smoothly applied to the skin surface) and “sustainability” (the property of sustaining the state of application to the skin).
Conventional cosmetic extenders are mostly natural ores and resins, which are not always satisfactory in terms of usability, stability, etc. For example, inorganic materials such as talc, mica, and sericite have catalytic activities, which can degrade perfumes or oils and cause smell change. Resin materials such as nylon powder and polyethylene powder are chemically stable, but have a problem of poor formability.
The BN powder is excellent in spreadability and sustainability, as compared with natural ores and resins.
This is because the BN powder not only has excellent lubricity, but also is flat-shaped and so has appropriate coverage and adhesion.
JP H5-186205 A (Patent Literature (PTL) 1) and JP H7-41311 A (PTL 2) propose manufacturing methods for such BN powders. These manufacturing methods are expected to supply chemically stable, flat-shaped BN powders.